Groundwater levels in Dviete floodplain during the summer and autumn of 2014
The last summer in Dviete floodplain was richer in precipitation than the summer of 2013. Subsequently, groundwater levels were slightly higher and more variable during the summer and autumn of 2014.
After extremely low spring floods, reaching a maximum at the end of March, a continued low-water period set in in Dviete floodplain. Decrease of the mean water level simultaneously in all monitoring wells was observed till the end of July. Occasionally there were temporary increases in water levels due to precipitation (e.g. during the 2nd decade of July), partly over-flooding the lowest wells. Still there was no significant increase of water level till October.
During the 2nd decade of October, due to increasing precipitation in Dviete river basin, the river over-flooded and a zone with the width of several tenth of meters at the right bank of Dviete oxbow near Putnu sala was under the water. Some lower wells were under the water for 1-2 weeks. Afterwards water levels in Dviete floodplain decreased again. The maximal level of autumn floods of 2014 was the same as during the spring floods (about 86.8 m above sea level).
Summarising results of the year 2014, it’s obvious, that most remarkable changes of the absolute height of groundwater level took place in the wells with highest location (No 1-4). Unlike two previous years, these wells were never under the water this year. While fluctuations of groundwater levels closer to the oxbow were twice smaller, and the lowest sites of the floodplain (wells No 10-15) were exposed to temporary flood water impact also this year.
Dāvis Gruberts
06.11.2014.
